An intraocular lens (IOL) is commonly used to replace the natural lens of the human eye when the condition of the natural lens so warrants. An IOL typically comprises an optic and fixation members. The fixation members are used to retain the optic in the correct optical position within the eye.
The fixation members must be biocompatible, resilient and not degrade in the presence of active ocular tissue. This severely limits the materials available for use as fixation members. For example, polypropylene, polyamide and extruded polymethylmethacrylate (PMMA) are suitable materials for the fixation members. However, fixation members of these materials, and in particular polypropylene, even though permanently formed into the desired shape, tend to relax over a period of time toward another configuration, which may be their initial or preformed configuration. This makes it difficult to maintain accurate control over the configuration of the fixation members. This in turn may cause problems with the implanted IOL, such as decentration or improper vaulting of the optic.